linux/fs/xfs/xfs_aops.c
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   1/*
   2 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
   3 * All Rights Reserved.
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it would be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write the Free Software Foundation,
  16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17 */
  18#include "xfs.h"
  19#include "xfs_log.h"
  20#include "xfs_sb.h"
  21#include "xfs_ag.h"
  22#include "xfs_trans.h"
  23#include "xfs_mount.h"
  24#include "xfs_bmap_btree.h"
  25#include "xfs_dinode.h"
  26#include "xfs_inode.h"
  27#include "xfs_inode_item.h"
  28#include "xfs_alloc.h"
  29#include "xfs_error.h"
  30#include "xfs_iomap.h"
  31#include "xfs_vnodeops.h"
  32#include "xfs_trace.h"
  33#include "xfs_bmap.h"
  34#include <linux/gfp.h>
  35#include <linux/mpage.h>
  36#include <linux/pagevec.h>
  37#include <linux/writeback.h>
  38
  39void
  40xfs_count_page_state(
  41        struct page             *page,
  42        int                     *delalloc,
  43        int                     *unwritten)
  44{
  45        struct buffer_head      *bh, *head;
  46
  47        *delalloc = *unwritten = 0;
  48
  49        bh = head = page_buffers(page);
  50        do {
  51                if (buffer_unwritten(bh))
  52                        (*unwritten) = 1;
  53                else if (buffer_delay(bh))
  54                        (*delalloc) = 1;
  55        } while ((bh = bh->b_this_page) != head);
  56}
  57
  58STATIC struct block_device *
  59xfs_find_bdev_for_inode(
  60        struct inode            *inode)
  61{
  62        struct xfs_inode        *ip = XFS_I(inode);
  63        struct xfs_mount        *mp = ip->i_mount;
  64
  65        if (XFS_IS_REALTIME_INODE(ip))
  66                return mp->m_rtdev_targp->bt_bdev;
  67        else
  68                return mp->m_ddev_targp->bt_bdev;
  69}
  70
  71/*
  72 * We're now finished for good with this ioend structure.
  73 * Update the page state via the associated buffer_heads,
  74 * release holds on the inode and bio, and finally free
  75 * up memory.  Do not use the ioend after this.
  76 */
  77STATIC void
  78xfs_destroy_ioend(
  79        xfs_ioend_t             *ioend)
  80{
  81        struct buffer_head      *bh, *next;
  82
  83        for (bh = ioend->io_buffer_head; bh; bh = next) {
  84                next = bh->b_private;
  85                bh->b_end_io(bh, !ioend->io_error);
  86        }
  87
  88        if (ioend->io_iocb) {
  89                if (ioend->io_isasync) {
  90                        aio_complete(ioend->io_iocb, ioend->io_error ?
  91                                        ioend->io_error : ioend->io_result, 0);
  92                }
  93                inode_dio_done(ioend->io_inode);
  94        }
  95
  96        mempool_free(ioend, xfs_ioend_pool);
  97}
  98
  99/*
 100 * Fast and loose check if this write could update the on-disk inode size.
 101 */
 102static inline bool xfs_ioend_is_append(struct xfs_ioend *ioend)
 103{
 104        return ioend->io_offset + ioend->io_size >
 105                XFS_I(ioend->io_inode)->i_d.di_size;
 106}
 107
 108STATIC int
 109xfs_setfilesize_trans_alloc(
 110        struct xfs_ioend        *ioend)
 111{
 112        struct xfs_mount        *mp = XFS_I(ioend->io_inode)->i_mount;
 113        struct xfs_trans        *tp;
 114        int                     error;
 115
 116        tp = xfs_trans_alloc(mp, XFS_TRANS_FSYNC_TS);
 117
 118        error = xfs_trans_reserve(tp, 0, XFS_FSYNC_TS_LOG_RES(mp), 0, 0, 0);
 119        if (error) {
 120                xfs_trans_cancel(tp, 0);
 121                return error;
 122        }
 123
 124        ioend->io_append_trans = tp;
 125
 126        /*
 127         * We will pass freeze protection with a transaction.  So tell lockdep
 128         * we released it.
 129         */
 130        rwsem_release(&ioend->io_inode->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
 131                      1, _THIS_IP_);
 132        /*
 133         * We hand off the transaction to the completion thread now, so
 134         * clear the flag here.
 135         */
 136        current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);
 137        return 0;
 138}
 139
 140/*
 141 * Update on-disk file size now that data has been written to disk.
 142 */
 143STATIC int
 144xfs_setfilesize(
 145        struct xfs_ioend        *ioend)
 146{
 147        struct xfs_inode        *ip = XFS_I(ioend->io_inode);
 148        struct xfs_trans        *tp = ioend->io_append_trans;
 149        xfs_fsize_t             isize;
 150
 151        /*
 152         * The transaction was allocated in the I/O submission thread,
 153         * thus we need to mark ourselves as beeing in a transaction
 154         * manually.
 155         */
 156        current_set_flags_nested(&tp->t_pflags, PF_FSTRANS);
 157
 158        xfs_ilock(ip, XFS_ILOCK_EXCL);
 159        isize = xfs_new_eof(ip, ioend->io_offset + ioend->io_size);
 160        if (!isize) {
 161                xfs_iunlock(ip, XFS_ILOCK_EXCL);
 162                xfs_trans_cancel(tp, 0);
 163                return 0;
 164        }
 165
 166        trace_xfs_setfilesize(ip, ioend->io_offset, ioend->io_size);
 167
 168        ip->i_d.di_size = isize;
 169        xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 170        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 171
 172        return xfs_trans_commit(tp, 0);
 173}
 174
 175/*
 176 * Schedule IO completion handling on the final put of an ioend.
 177 *
 178 * If there is no work to do we might as well call it a day and free the
 179 * ioend right now.
 180 */
 181STATIC void
 182xfs_finish_ioend(
 183        struct xfs_ioend        *ioend)
 184{
 185        if (atomic_dec_and_test(&ioend->io_remaining)) {
 186                struct xfs_mount        *mp = XFS_I(ioend->io_inode)->i_mount;
 187
 188                if (ioend->io_type == XFS_IO_UNWRITTEN)
 189                        queue_work(mp->m_unwritten_workqueue, &ioend->io_work);
 190                else if (ioend->io_append_trans)
 191                        queue_work(mp->m_data_workqueue, &ioend->io_work);
 192                else
 193                        xfs_destroy_ioend(ioend);
 194        }
 195}
 196
 197/*
 198 * IO write completion.
 199 */
 200STATIC void
 201xfs_end_io(
 202        struct work_struct *work)
 203{
 204        xfs_ioend_t     *ioend = container_of(work, xfs_ioend_t, io_work);
 205        struct xfs_inode *ip = XFS_I(ioend->io_inode);
 206        int             error = 0;
 207
 208        if (ioend->io_append_trans) {
 209                /*
 210                 * We've got freeze protection passed with the transaction.
 211                 * Tell lockdep about it.
 212                 */
 213                rwsem_acquire_read(
 214                        &ioend->io_inode->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
 215                        0, 1, _THIS_IP_);
 216        }
 217        if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
 218                ioend->io_error = -EIO;
 219                goto done;
 220        }
 221        if (ioend->io_error)
 222                goto done;
 223
 224        /*
 225         * For unwritten extents we need to issue transactions to convert a
 226         * range to normal written extens after the data I/O has finished.
 227         */
 228        if (ioend->io_type == XFS_IO_UNWRITTEN) {
 229                /*
 230                 * For buffered I/O we never preallocate a transaction when
 231                 * doing the unwritten extent conversion, but for direct I/O
 232                 * we do not know if we are converting an unwritten extent
 233                 * or not at the point where we preallocate the transaction.
 234                 */
 235                if (ioend->io_append_trans) {
 236                        ASSERT(ioend->io_isdirect);
 237
 238                        current_set_flags_nested(
 239                                &ioend->io_append_trans->t_pflags, PF_FSTRANS);
 240                        xfs_trans_cancel(ioend->io_append_trans, 0);
 241                }
 242
 243                error = xfs_iomap_write_unwritten(ip, ioend->io_offset,
 244                                                 ioend->io_size);
 245                if (error) {
 246                        ioend->io_error = -error;
 247                        goto done;
 248                }
 249        } else if (ioend->io_append_trans) {
 250                error = xfs_setfilesize(ioend);
 251                if (error)
 252                        ioend->io_error = -error;
 253        } else {
 254                ASSERT(!xfs_ioend_is_append(ioend));
 255        }
 256
 257done:
 258        xfs_destroy_ioend(ioend);
 259}
 260
 261/*
 262 * Call IO completion handling in caller context on the final put of an ioend.
 263 */
 264STATIC void
 265xfs_finish_ioend_sync(
 266        struct xfs_ioend        *ioend)
 267{
 268        if (atomic_dec_and_test(&ioend->io_remaining))
 269                xfs_end_io(&ioend->io_work);
 270}
 271
 272/*
 273 * Allocate and initialise an IO completion structure.
 274 * We need to track unwritten extent write completion here initially.
 275 * We'll need to extend this for updating the ondisk inode size later
 276 * (vs. incore size).
 277 */
 278STATIC xfs_ioend_t *
 279xfs_alloc_ioend(
 280        struct inode            *inode,
 281        unsigned int            type)
 282{
 283        xfs_ioend_t             *ioend;
 284
 285        ioend = mempool_alloc(xfs_ioend_pool, GFP_NOFS);
 286
 287        /*
 288         * Set the count to 1 initially, which will prevent an I/O
 289         * completion callback from happening before we have started
 290         * all the I/O from calling the completion routine too early.
 291         */
 292        atomic_set(&ioend->io_remaining, 1);
 293        ioend->io_isasync = 0;
 294        ioend->io_isdirect = 0;
 295        ioend->io_error = 0;
 296        ioend->io_list = NULL;
 297        ioend->io_type = type;
 298        ioend->io_inode = inode;
 299        ioend->io_buffer_head = NULL;
 300        ioend->io_buffer_tail = NULL;
 301        ioend->io_offset = 0;
 302        ioend->io_size = 0;
 303        ioend->io_iocb = NULL;
 304        ioend->io_result = 0;
 305        ioend->io_append_trans = NULL;
 306
 307        INIT_WORK(&ioend->io_work, xfs_end_io);
 308        return ioend;
 309}
 310
 311STATIC int
 312xfs_map_blocks(
 313        struct inode            *inode,
 314        loff_t                  offset,
 315        struct xfs_bmbt_irec    *imap,
 316        int                     type,
 317        int                     nonblocking)
 318{
 319        struct xfs_inode        *ip = XFS_I(inode);
 320        struct xfs_mount        *mp = ip->i_mount;
 321        ssize_t                 count = 1 << inode->i_blkbits;
 322        xfs_fileoff_t           offset_fsb, end_fsb;
 323        int                     error = 0;
 324        int                     bmapi_flags = XFS_BMAPI_ENTIRE;
 325        int                     nimaps = 1;
 326
 327        if (XFS_FORCED_SHUTDOWN(mp))
 328                return -XFS_ERROR(EIO);
 329
 330        if (type == XFS_IO_UNWRITTEN)
 331                bmapi_flags |= XFS_BMAPI_IGSTATE;
 332
 333        if (!xfs_ilock_nowait(ip, XFS_ILOCK_SHARED)) {
 334                if (nonblocking)
 335                        return -XFS_ERROR(EAGAIN);
 336                xfs_ilock(ip, XFS_ILOCK_SHARED);
 337        }
 338
 339        ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
 340               (ip->i_df.if_flags & XFS_IFEXTENTS));
 341        ASSERT(offset <= mp->m_super->s_maxbytes);
 342
 343        if (offset + count > mp->m_super->s_maxbytes)
 344                count = mp->m_super->s_maxbytes - offset;
 345        end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
 346        offset_fsb = XFS_B_TO_FSBT(mp, offset);
 347        error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
 348                                imap, &nimaps, bmapi_flags);
 349        xfs_iunlock(ip, XFS_ILOCK_SHARED);
 350
 351        if (error)
 352                return -XFS_ERROR(error);
 353
 354        if (type == XFS_IO_DELALLOC &&
 355            (!nimaps || isnullstartblock(imap->br_startblock))) {
 356                error = xfs_iomap_write_allocate(ip, offset, count, imap);
 357                if (!error)
 358                        trace_xfs_map_blocks_alloc(ip, offset, count, type, imap);
 359                return -XFS_ERROR(error);
 360        }
 361
 362#ifdef DEBUG
 363        if (type == XFS_IO_UNWRITTEN) {
 364                ASSERT(nimaps);
 365                ASSERT(imap->br_startblock != HOLESTARTBLOCK);
 366                ASSERT(imap->br_startblock != DELAYSTARTBLOCK);
 367        }
 368#endif
 369        if (nimaps)
 370                trace_xfs_map_blocks_found(ip, offset, count, type, imap);
 371        return 0;
 372}
 373
 374STATIC int
 375xfs_imap_valid(
 376        struct inode            *inode,
 377        struct xfs_bmbt_irec    *imap,
 378        xfs_off_t               offset)
 379{
 380        offset >>= inode->i_blkbits;
 381
 382        return offset >= imap->br_startoff &&
 383                offset < imap->br_startoff + imap->br_blockcount;
 384}
 385
 386/*
 387 * BIO completion handler for buffered IO.
 388 */
 389STATIC void
 390xfs_end_bio(
 391        struct bio              *bio,
 392        int                     error)
 393{
 394        xfs_ioend_t             *ioend = bio->bi_private;
 395
 396        ASSERT(atomic_read(&bio->bi_cnt) >= 1);
 397        ioend->io_error = test_bit(BIO_UPTODATE, &bio->bi_flags) ? 0 : error;
 398
 399        /* Toss bio and pass work off to an xfsdatad thread */
 400        bio->bi_private = NULL;
 401        bio->bi_end_io = NULL;
 402        bio_put(bio);
 403
 404        xfs_finish_ioend(ioend);
 405}
 406
 407STATIC void
 408xfs_submit_ioend_bio(
 409        struct writeback_control *wbc,
 410        xfs_ioend_t             *ioend,
 411        struct bio              *bio)
 412{
 413        atomic_inc(&ioend->io_remaining);
 414        bio->bi_private = ioend;
 415        bio->bi_end_io = xfs_end_bio;
 416        submit_bio(wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE, bio);
 417}
 418
 419STATIC struct bio *
 420xfs_alloc_ioend_bio(
 421        struct buffer_head      *bh)
 422{
 423        int                     nvecs = bio_get_nr_vecs(bh->b_bdev);
 424        struct bio              *bio = bio_alloc(GFP_NOIO, nvecs);
 425
 426        ASSERT(bio->bi_private == NULL);
 427        bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
 428        bio->bi_bdev = bh->b_bdev;
 429        return bio;
 430}
 431
 432STATIC void
 433xfs_start_buffer_writeback(
 434        struct buffer_head      *bh)
 435{
 436        ASSERT(buffer_mapped(bh));
 437        ASSERT(buffer_locked(bh));
 438        ASSERT(!buffer_delay(bh));
 439        ASSERT(!buffer_unwritten(bh));
 440
 441        mark_buffer_async_write(bh);
 442        set_buffer_uptodate(bh);
 443        clear_buffer_dirty(bh);
 444}
 445
 446STATIC void
 447xfs_start_page_writeback(
 448        struct page             *page,
 449        int                     clear_dirty,
 450        int                     buffers)
 451{
 452        ASSERT(PageLocked(page));
 453        ASSERT(!PageWriteback(page));
 454        if (clear_dirty)
 455                clear_page_dirty_for_io(page);
 456        set_page_writeback(page);
 457        unlock_page(page);
 458        /* If no buffers on the page are to be written, finish it here */
 459        if (!buffers)
 460                end_page_writeback(page);
 461}
 462
 463static inline int bio_add_buffer(struct bio *bio, struct buffer_head *bh)
 464{
 465        return bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
 466}
 467
 468/*
 469 * Submit all of the bios for all of the ioends we have saved up, covering the
 470 * initial writepage page and also any probed pages.
 471 *
 472 * Because we may have multiple ioends spanning a page, we need to start
 473 * writeback on all the buffers before we submit them for I/O. If we mark the
 474 * buffers as we got, then we can end up with a page that only has buffers
 475 * marked async write and I/O complete on can occur before we mark the other
 476 * buffers async write.
 477 *
 478 * The end result of this is that we trip a bug in end_page_writeback() because
 479 * we call it twice for the one page as the code in end_buffer_async_write()
 480 * assumes that all buffers on the page are started at the same time.
 481 *
 482 * The fix is two passes across the ioend list - one to start writeback on the
 483 * buffer_heads, and then submit them for I/O on the second pass.
 484 */
 485STATIC void
 486xfs_submit_ioend(
 487        struct writeback_control *wbc,
 488        xfs_ioend_t             *ioend)
 489{
 490        xfs_ioend_t             *head = ioend;
 491        xfs_ioend_t             *next;
 492        struct buffer_head      *bh;
 493        struct bio              *bio;
 494        sector_t                lastblock = 0;
 495
 496        /* Pass 1 - start writeback */
 497        do {
 498                next = ioend->io_list;
 499                for (bh = ioend->io_buffer_head; bh; bh = bh->b_private)
 500                        xfs_start_buffer_writeback(bh);
 501        } while ((ioend = next) != NULL);
 502
 503        /* Pass 2 - submit I/O */
 504        ioend = head;
 505        do {
 506                next = ioend->io_list;
 507                bio = NULL;
 508
 509                for (bh = ioend->io_buffer_head; bh; bh = bh->b_private) {
 510
 511                        if (!bio) {
 512 retry:
 513                                bio = xfs_alloc_ioend_bio(bh);
 514                        } else if (bh->b_blocknr != lastblock + 1) {
 515                                xfs_submit_ioend_bio(wbc, ioend, bio);
 516                                goto retry;
 517                        }
 518
 519                        if (bio_add_buffer(bio, bh) != bh->b_size) {
 520                                xfs_submit_ioend_bio(wbc, ioend, bio);
 521                                goto retry;
 522                        }
 523
 524                        lastblock = bh->b_blocknr;
 525                }
 526                if (bio)
 527                        xfs_submit_ioend_bio(wbc, ioend, bio);
 528                xfs_finish_ioend(ioend);
 529        } while ((ioend = next) != NULL);
 530}
 531
 532/*
 533 * Cancel submission of all buffer_heads so far in this endio.
 534 * Toss the endio too.  Only ever called for the initial page
 535 * in a writepage request, so only ever one page.
 536 */
 537STATIC void
 538xfs_cancel_ioend(
 539        xfs_ioend_t             *ioend)
 540{
 541        xfs_ioend_t             *next;
 542        struct buffer_head      *bh, *next_bh;
 543
 544        do {
 545                next = ioend->io_list;
 546                bh = ioend->io_buffer_head;
 547                do {
 548                        next_bh = bh->b_private;
 549                        clear_buffer_async_write(bh);
 550                        unlock_buffer(bh);
 551                } while ((bh = next_bh) != NULL);
 552
 553                mempool_free(ioend, xfs_ioend_pool);
 554        } while ((ioend = next) != NULL);
 555}
 556
 557/*
 558 * Test to see if we've been building up a completion structure for
 559 * earlier buffers -- if so, we try to append to this ioend if we
 560 * can, otherwise we finish off any current ioend and start another.
 561 * Return true if we've finished the given ioend.
 562 */
 563STATIC void
 564xfs_add_to_ioend(
 565        struct inode            *inode,
 566        struct buffer_head      *bh,
 567        xfs_off_t               offset,
 568        unsigned int            type,
 569        xfs_ioend_t             **result,
 570        int                     need_ioend)
 571{
 572        xfs_ioend_t             *ioend = *result;
 573
 574        if (!ioend || need_ioend || type != ioend->io_type) {
 575                xfs_ioend_t     *previous = *result;
 576
 577                ioend = xfs_alloc_ioend(inode, type);
 578                ioend->io_offset = offset;
 579                ioend->io_buffer_head = bh;
 580                ioend->io_buffer_tail = bh;
 581                if (previous)
 582                        previous->io_list = ioend;
 583                *result = ioend;
 584        } else {
 585                ioend->io_buffer_tail->b_private = bh;
 586                ioend->io_buffer_tail = bh;
 587        }
 588
 589        bh->b_private = NULL;
 590        ioend->io_size += bh->b_size;
 591}
 592
 593STATIC void
 594xfs_map_buffer(
 595        struct inode            *inode,
 596        struct buffer_head      *bh,
 597        struct xfs_bmbt_irec    *imap,
 598        xfs_off_t               offset)
 599{
 600        sector_t                bn;
 601        struct xfs_mount        *m = XFS_I(inode)->i_mount;
 602        xfs_off_t               iomap_offset = XFS_FSB_TO_B(m, imap->br_startoff);
 603        xfs_daddr_t             iomap_bn = xfs_fsb_to_db(XFS_I(inode), imap->br_startblock);
 604
 605        ASSERT(imap->br_startblock != HOLESTARTBLOCK);
 606        ASSERT(imap->br_startblock != DELAYSTARTBLOCK);
 607
 608        bn = (iomap_bn >> (inode->i_blkbits - BBSHIFT)) +
 609              ((offset - iomap_offset) >> inode->i_blkbits);
 610
 611        ASSERT(bn || XFS_IS_REALTIME_INODE(XFS_I(inode)));
 612
 613        bh->b_blocknr = bn;
 614        set_buffer_mapped(bh);
 615}
 616
 617STATIC void
 618xfs_map_at_offset(
 619        struct inode            *inode,
 620        struct buffer_head      *bh,
 621        struct xfs_bmbt_irec    *imap,
 622        xfs_off_t               offset)
 623{
 624        ASSERT(imap->br_startblock != HOLESTARTBLOCK);
 625        ASSERT(imap->br_startblock != DELAYSTARTBLOCK);
 626
 627        xfs_map_buffer(inode, bh, imap, offset);
 628        set_buffer_mapped(bh);
 629        clear_buffer_delay(bh);
 630        clear_buffer_unwritten(bh);
 631}
 632
 633/*
 634 * Test if a given page is suitable for writing as part of an unwritten
 635 * or delayed allocate extent.
 636 */
 637STATIC int
 638xfs_check_page_type(
 639        struct page             *page,
 640        unsigned int            type)
 641{
 642        if (PageWriteback(page))
 643                return 0;
 644
 645        if (page->mapping && page_has_buffers(page)) {
 646                struct buffer_head      *bh, *head;
 647                int                     acceptable = 0;
 648
 649                bh = head = page_buffers(page);
 650                do {
 651                        if (buffer_unwritten(bh))
 652                                acceptable += (type == XFS_IO_UNWRITTEN);
 653                        else if (buffer_delay(bh))
 654                                acceptable += (type == XFS_IO_DELALLOC);
 655                        else if (buffer_dirty(bh) && buffer_mapped(bh))
 656                                acceptable += (type == XFS_IO_OVERWRITE);
 657                        else
 658                                break;
 659                } while ((bh = bh->b_this_page) != head);
 660
 661                if (acceptable)
 662                        return 1;
 663        }
 664
 665        return 0;
 666}
 667
 668/*
 669 * Allocate & map buffers for page given the extent map. Write it out.
 670 * except for the original page of a writepage, this is called on
 671 * delalloc/unwritten pages only, for the original page it is possible
 672 * that the page has no mapping at all.
 673 */
 674STATIC int
 675xfs_convert_page(
 676        struct inode            *inode,
 677        struct page             *page,
 678        loff_t                  tindex,
 679        struct xfs_bmbt_irec    *imap,
 680        xfs_ioend_t             **ioendp,
 681        struct writeback_control *wbc)
 682{
 683        struct buffer_head      *bh, *head;
 684        xfs_off_t               end_offset;
 685        unsigned long           p_offset;
 686        unsigned int            type;
 687        int                     len, page_dirty;
 688        int                     count = 0, done = 0, uptodate = 1;
 689        xfs_off_t               offset = page_offset(page);
 690
 691        if (page->index != tindex)
 692                goto fail;
 693        if (!trylock_page(page))
 694                goto fail;
 695        if (PageWriteback(page))
 696                goto fail_unlock_page;
 697        if (page->mapping != inode->i_mapping)
 698                goto fail_unlock_page;
 699        if (!xfs_check_page_type(page, (*ioendp)->io_type))
 700                goto fail_unlock_page;
 701
 702        /*
 703         * page_dirty is initially a count of buffers on the page before
 704         * EOF and is decremented as we move each into a cleanable state.
 705         *
 706         * Derivation:
 707         *
 708         * End offset is the highest offset that this page should represent.
 709         * If we are on the last page, (end_offset & (PAGE_CACHE_SIZE - 1))
 710         * will evaluate non-zero and be less than PAGE_CACHE_SIZE and
 711         * hence give us the correct page_dirty count. On any other page,
 712         * it will be zero and in that case we need page_dirty to be the
 713         * count of buffers on the page.
 714         */
 715        end_offset = min_t(unsigned long long,
 716                        (xfs_off_t)(page->index + 1) << PAGE_CACHE_SHIFT,
 717                        i_size_read(inode));
 718
 719        len = 1 << inode->i_blkbits;
 720        p_offset = min_t(unsigned long, end_offset & (PAGE_CACHE_SIZE - 1),
 721                                        PAGE_CACHE_SIZE);
 722        p_offset = p_offset ? roundup(p_offset, len) : PAGE_CACHE_SIZE;
 723        page_dirty = p_offset / len;
 724
 725        bh = head = page_buffers(page);
 726        do {
 727                if (offset >= end_offset)
 728                        break;
 729                if (!buffer_uptodate(bh))
 730                        uptodate = 0;
 731                if (!(PageUptodate(page) || buffer_uptodate(bh))) {
 732                        done = 1;
 733                        continue;
 734                }
 735
 736                if (buffer_unwritten(bh) || buffer_delay(bh) ||
 737                    buffer_mapped(bh)) {
 738                        if (buffer_unwritten(bh))
 739                                type = XFS_IO_UNWRITTEN;
 740                        else if (buffer_delay(bh))
 741                                type = XFS_IO_DELALLOC;
 742                        else
 743                                type = XFS_IO_OVERWRITE;
 744
 745                        if (!xfs_imap_valid(inode, imap, offset)) {
 746                                done = 1;
 747                                continue;
 748                        }
 749
 750                        lock_buffer(bh);
 751                        if (type != XFS_IO_OVERWRITE)
 752                                xfs_map_at_offset(inode, bh, imap, offset);
 753                        xfs_add_to_ioend(inode, bh, offset, type,
 754                                         ioendp, done);
 755
 756                        page_dirty--;
 757                        count++;
 758                } else {
 759                        done = 1;
 760                }
 761        } while (offset += len, (bh = bh->b_this_page) != head);
 762
 763        if (uptodate && bh == head)
 764                SetPageUptodate(page);
 765
 766        if (count) {
 767                if (--wbc->nr_to_write <= 0 &&
 768                    wbc->sync_mode == WB_SYNC_NONE)
 769                        done = 1;
 770        }
 771        xfs_start_page_writeback(page, !page_dirty, count);
 772
 773        return done;
 774 fail_unlock_page:
 775        unlock_page(page);
 776 fail:
 777        return 1;
 778}
 779
 780/*
 781 * Convert & write out a cluster of pages in the same extent as defined
 782 * by mp and following the start page.
 783 */
 784STATIC void
 785xfs_cluster_write(
 786        struct inode            *inode,
 787        pgoff_t                 tindex,
 788        struct xfs_bmbt_irec    *imap,
 789        xfs_ioend_t             **ioendp,
 790        struct writeback_control *wbc,
 791        pgoff_t                 tlast)
 792{
 793        struct pagevec          pvec;
 794        int                     done = 0, i;
 795
 796        pagevec_init(&pvec, 0);
 797        while (!done && tindex <= tlast) {
 798                unsigned len = min_t(pgoff_t, PAGEVEC_SIZE, tlast - tindex + 1);
 799
 800                if (!pagevec_lookup(&pvec, inode->i_mapping, tindex, len))
 801                        break;
 802
 803                for (i = 0; i < pagevec_count(&pvec); i++) {
 804                        done = xfs_convert_page(inode, pvec.pages[i], tindex++,
 805                                        imap, ioendp, wbc);
 806                        if (done)
 807                                break;
 808                }
 809
 810                pagevec_release(&pvec);
 811                cond_resched();
 812        }
 813}
 814
 815STATIC void
 816xfs_vm_invalidatepage(
 817        struct page             *page,
 818        unsigned long           offset)
 819{
 820        trace_xfs_invalidatepage(page->mapping->host, page, offset);
 821        block_invalidatepage(page, offset);
 822}
 823
 824/*
 825 * If the page has delalloc buffers on it, we need to punch them out before we
 826 * invalidate the page. If we don't, we leave a stale delalloc mapping on the
 827 * inode that can trip a BUG() in xfs_get_blocks() later on if a direct IO read
 828 * is done on that same region - the delalloc extent is returned when none is
 829 * supposed to be there.
 830 *
 831 * We prevent this by truncating away the delalloc regions on the page before
 832 * invalidating it. Because they are delalloc, we can do this without needing a
 833 * transaction. Indeed - if we get ENOSPC errors, we have to be able to do this
 834 * truncation without a transaction as there is no space left for block
 835 * reservation (typically why we see a ENOSPC in writeback).
 836 *
 837 * This is not a performance critical path, so for now just do the punching a
 838 * buffer head at a time.
 839 */
 840STATIC void
 841xfs_aops_discard_page(
 842        struct page             *page)
 843{
 844        struct inode            *inode = page->mapping->host;
 845        struct xfs_inode        *ip = XFS_I(inode);
 846        struct buffer_head      *bh, *head;
 847        loff_t                  offset = page_offset(page);
 848
 849        if (!xfs_check_page_type(page, XFS_IO_DELALLOC))
 850                goto out_invalidate;
 851
 852        if (XFS_FORCED_SHUTDOWN(ip->i_mount))
 853                goto out_invalidate;
 854
 855        xfs_alert(ip->i_mount,
 856                "page discard on page %p, inode 0x%llx, offset %llu.",
 857                        page, ip->i_ino, offset);
 858
 859        xfs_ilock(ip, XFS_ILOCK_EXCL);
 860        bh = head = page_buffers(page);
 861        do {
 862                int             error;
 863                xfs_fileoff_t   start_fsb;
 864
 865                if (!buffer_delay(bh))
 866                        goto next_buffer;
 867
 868                start_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
 869                error = xfs_bmap_punch_delalloc_range(ip, start_fsb, 1);
 870                if (error) {
 871                        /* something screwed, just bail */
 872                        if (!XFS_FORCED_SHUTDOWN(ip->i_mount)) {
 873                                xfs_alert(ip->i_mount,
 874                        "page discard unable to remove delalloc mapping.");
 875                        }
 876                        break;
 877                }
 878next_buffer:
 879                offset += 1 << inode->i_blkbits;
 880
 881        } while ((bh = bh->b_this_page) != head);
 882
 883        xfs_iunlock(ip, XFS_ILOCK_EXCL);
 884out_invalidate:
 885        xfs_vm_invalidatepage(page, 0);
 886        return;
 887}
 888
 889/*
 890 * Write out a dirty page.
 891 *
 892 * For delalloc space on the page we need to allocate space and flush it.
 893 * For unwritten space on the page we need to start the conversion to
 894 * regular allocated space.
 895 * For any other dirty buffer heads on the page we should flush them.
 896 */
 897STATIC int
 898xfs_vm_writepage(
 899        struct page             *page,
 900        struct writeback_control *wbc)
 901{
 902        struct inode            *inode = page->mapping->host;
 903        struct buffer_head      *bh, *head;
 904        struct xfs_bmbt_irec    imap;
 905        xfs_ioend_t             *ioend = NULL, *iohead = NULL;
 906        loff_t                  offset;
 907        unsigned int            type;
 908        __uint64_t              end_offset;
 909        pgoff_t                 end_index, last_index;
 910        ssize_t                 len;
 911        int                     err, imap_valid = 0, uptodate = 1;
 912        int                     count = 0;
 913        int                     nonblocking = 0;
 914
 915        trace_xfs_writepage(inode, page, 0);
 916
 917        ASSERT(page_has_buffers(page));
 918
 919        /*
 920         * Refuse to write the page out if we are called from reclaim context.
 921         *
 922         * This avoids stack overflows when called from deeply used stacks in
 923         * random callers for direct reclaim or memcg reclaim.  We explicitly
 924         * allow reclaim from kswapd as the stack usage there is relatively low.
 925         *
 926         * This should never happen except in the case of a VM regression so
 927         * warn about it.
 928         */
 929        if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) ==
 930                        PF_MEMALLOC))
 931                goto redirty;
 932
 933        /*
 934         * Given that we do not allow direct reclaim to call us, we should
 935         * never be called while in a filesystem transaction.
 936         */
 937        if (WARN_ON(current->flags & PF_FSTRANS))
 938                goto redirty;
 939
 940        /* Is this page beyond the end of the file? */
 941        offset = i_size_read(inode);
 942        end_index = offset >> PAGE_CACHE_SHIFT;
 943        last_index = (offset - 1) >> PAGE_CACHE_SHIFT;
 944        if (page->index >= end_index) {
 945                unsigned offset_into_page = offset & (PAGE_CACHE_SIZE - 1);
 946
 947                /*
 948                 * Just skip the page if it is fully outside i_size, e.g. due
 949                 * to a truncate operation that is in progress.
 950                 */
 951                if (page->index >= end_index + 1 || offset_into_page == 0) {
 952                        unlock_page(page);
 953                        return 0;
 954                }
 955
 956                /*
 957                 * The page straddles i_size.  It must be zeroed out on each
 958                 * and every writepage invocation because it may be mmapped.
 959                 * "A file is mapped in multiples of the page size.  For a file
 960                 * that is not a multiple of the  page size, the remaining
 961                 * memory is zeroed when mapped, and writes to that region are
 962                 * not written out to the file."
 963                 */
 964                zero_user_segment(page, offset_into_page, PAGE_CACHE_SIZE);
 965        }
 966
 967        end_offset = min_t(unsigned long long,
 968                        (xfs_off_t)(page->index + 1) << PAGE_CACHE_SHIFT,
 969                        offset);
 970        len = 1 << inode->i_blkbits;
 971
 972        bh = head = page_buffers(page);
 973        offset = page_offset(page);
 974        type = XFS_IO_OVERWRITE;
 975
 976        if (wbc->sync_mode == WB_SYNC_NONE)
 977                nonblocking = 1;
 978
 979        do {
 980                int new_ioend = 0;
 981
 982                if (offset >= end_offset)
 983                        break;
 984                if (!buffer_uptodate(bh))
 985                        uptodate = 0;
 986
 987                /*
 988                 * set_page_dirty dirties all buffers in a page, independent
 989                 * of their state.  The dirty state however is entirely
 990                 * meaningless for holes (!mapped && uptodate), so skip
 991                 * buffers covering holes here.
 992                 */
 993                if (!buffer_mapped(bh) && buffer_uptodate(bh)) {
 994                        imap_valid = 0;
 995                        continue;
 996                }
 997
 998                if (buffer_unwritten(bh)) {
 999                        if (type != XFS_IO_UNWRITTEN) {
1000                                type = XFS_IO_UNWRITTEN;
1001                                imap_valid = 0;
1002                        }
1003                } else if (buffer_delay(bh)) {
1004                        if (type != XFS_IO_DELALLOC) {
1005                                type = XFS_IO_DELALLOC;
1006                                imap_valid = 0;
1007                        }
1008                } else if (buffer_uptodate(bh)) {
1009                        if (type != XFS_IO_OVERWRITE) {
1010                                type = XFS_IO_OVERWRITE;
1011                                imap_valid = 0;
1012                        }
1013                } else {
1014                        if (PageUptodate(page))
1015                                ASSERT(buffer_mapped(bh));
1016                        /*
1017                         * This buffer is not uptodate and will not be
1018                         * written to disk.  Ensure that we will put any
1019                         * subsequent writeable buffers into a new
1020                         * ioend.
1021                         */
1022                        imap_valid = 0;
1023                        continue;
1024                }
1025
1026                if (imap_valid)
1027                        imap_valid = xfs_imap_valid(inode, &imap, offset);
1028                if (!imap_valid) {
1029                        /*
1030                         * If we didn't have a valid mapping then we need to
1031                         * put the new mapping into a separate ioend structure.
1032                         * This ensures non-contiguous extents always have
1033                         * separate ioends, which is particularly important
1034                         * for unwritten extent conversion at I/O completion
1035                         * time.
1036                         */
1037                        new_ioend = 1;
1038                        err = xfs_map_blocks(inode, offset, &imap, type,
1039                                             nonblocking);
1040                        if (err)
1041                                goto error;
1042                        imap_valid = xfs_imap_valid(inode, &imap, offset);
1043                }
1044                if (imap_valid) {
1045                        lock_buffer(bh);
1046                        if (type != XFS_IO_OVERWRITE)
1047                                xfs_map_at_offset(inode, bh, &imap, offset);
1048                        xfs_add_to_ioend(inode, bh, offset, type, &ioend,
1049                                         new_ioend);
1050                        count++;
1051                }
1052
1053                if (!iohead)
1054                        iohead = ioend;
1055
1056        } while (offset += len, ((bh = bh->b_this_page) != head));
1057
1058        if (uptodate && bh == head)
1059                SetPageUptodate(page);
1060
1061        xfs_start_page_writeback(page, 1, count);
1062
1063        if (ioend && imap_valid) {
1064                xfs_off_t               end_index;
1065
1066                end_index = imap.br_startoff + imap.br_blockcount;
1067
1068                /* to bytes */
1069                end_index <<= inode->i_blkbits;
1070
1071                /* to pages */
1072                end_index = (end_index - 1) >> PAGE_CACHE_SHIFT;
1073
1074                /* check against file size */
1075                if (end_index > last_index)
1076                        end_index = last_index;
1077
1078                xfs_cluster_write(inode, page->index + 1, &imap, &ioend,
1079                                  wbc, end_index);
1080        }
1081
1082        if (iohead) {
1083                /*
1084                 * Reserve log space if we might write beyond the on-disk
1085                 * inode size.
1086                 */
1087                if (ioend->io_type != XFS_IO_UNWRITTEN &&
1088                    xfs_ioend_is_append(ioend)) {
1089                        err = xfs_setfilesize_trans_alloc(ioend);
1090                        if (err)
1091                                goto error;
1092                }
1093
1094                xfs_submit_ioend(wbc, iohead);
1095        }
1096
1097        return 0;
1098
1099error:
1100        if (iohead)
1101                xfs_cancel_ioend(iohead);
1102
1103        if (err == -EAGAIN)
1104                goto redirty;
1105
1106        xfs_aops_discard_page(page);
1107        ClearPageUptodate(page);
1108        unlock_page(page);
1109        return err;
1110
1111redirty:
1112        redirty_page_for_writepage(wbc, page);
1113        unlock_page(page);
1114        return 0;
1115}
1116
1117STATIC int
1118xfs_vm_writepages(
1119        struct address_space    *mapping,
1120        struct writeback_control *wbc)
1121{
1122        xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
1123        return generic_writepages(mapping, wbc);
1124}
1125
1126/*
1127 * Called to move a page into cleanable state - and from there
1128 * to be released. The page should already be clean. We always
1129 * have buffer heads in this call.
1130 *
1131 * Returns 1 if the page is ok to release, 0 otherwise.
1132 */
1133STATIC int
1134xfs_vm_releasepage(
1135        struct page             *page,
1136        gfp_t                   gfp_mask)
1137{
1138        int                     delalloc, unwritten;
1139
1140        trace_xfs_releasepage(page->mapping->host, page, 0);
1141
1142        xfs_count_page_state(page, &delalloc, &unwritten);
1143
1144        if (WARN_ON(delalloc))
1145                return 0;
1146        if (WARN_ON(unwritten))
1147                return 0;
1148
1149        return try_to_free_buffers(page);
1150}
1151
1152STATIC int
1153__xfs_get_blocks(
1154        struct inode            *inode,
1155        sector_t                iblock,
1156        struct buffer_head      *bh_result,
1157        int                     create,
1158        int                     direct)
1159{
1160        struct xfs_inode        *ip = XFS_I(inode);
1161        struct xfs_mount        *mp = ip->i_mount;
1162        xfs_fileoff_t           offset_fsb, end_fsb;
1163        int                     error = 0;
1164        int                     lockmode = 0;
1165        struct xfs_bmbt_irec    imap;
1166        int                     nimaps = 1;
1167        xfs_off_t               offset;
1168        ssize_t                 size;
1169        int                     new = 0;
1170
1171        if (XFS_FORCED_SHUTDOWN(mp))
1172                return -XFS_ERROR(EIO);
1173
1174        offset = (xfs_off_t)iblock << inode->i_blkbits;
1175        ASSERT(bh_result->b_size >= (1 << inode->i_blkbits));
1176        size = bh_result->b_size;
1177
1178        if (!create && direct && offset >= i_size_read(inode))
1179                return 0;
1180
1181        /*
1182         * Direct I/O is usually done on preallocated files, so try getting
1183         * a block mapping without an exclusive lock first.  For buffered
1184         * writes we already have the exclusive iolock anyway, so avoiding
1185         * a lock roundtrip here by taking the ilock exclusive from the
1186         * beginning is a useful micro optimization.
1187         */
1188        if (create && !direct) {
1189                lockmode = XFS_ILOCK_EXCL;
1190                xfs_ilock(ip, lockmode);
1191        } else {
1192                lockmode = xfs_ilock_map_shared(ip);
1193        }
1194
1195        ASSERT(offset <= mp->m_super->s_maxbytes);
1196        if (offset + size > mp->m_super->s_maxbytes)
1197                size = mp->m_super->s_maxbytes - offset;
1198        end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + size);
1199        offset_fsb = XFS_B_TO_FSBT(mp, offset);
1200
1201        error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
1202                                &imap, &nimaps, XFS_BMAPI_ENTIRE);
1203        if (error)
1204                goto out_unlock;
1205
1206        if (create &&
1207            (!nimaps ||
1208             (imap.br_startblock == HOLESTARTBLOCK ||
1209              imap.br_startblock == DELAYSTARTBLOCK))) {
1210                if (direct || xfs_get_extsz_hint(ip)) {
1211                        /*
1212                         * Drop the ilock in preparation for starting the block
1213                         * allocation transaction.  It will be retaken
1214                         * exclusively inside xfs_iomap_write_direct for the
1215                         * actual allocation.
1216                         */
1217                        xfs_iunlock(ip, lockmode);
1218                        error = xfs_iomap_write_direct(ip, offset, size,
1219                                                       &imap, nimaps);
1220                        if (error)
1221                                return -error;
1222                        new = 1;
1223                } else {
1224                        /*
1225                         * Delalloc reservations do not require a transaction,
1226                         * we can go on without dropping the lock here. If we
1227                         * are allocating a new delalloc block, make sure that
1228                         * we set the new flag so that we mark the buffer new so
1229                         * that we know that it is newly allocated if the write
1230                         * fails.
1231                         */
1232                        if (nimaps && imap.br_startblock == HOLESTARTBLOCK)
1233                                new = 1;
1234                        error = xfs_iomap_write_delay(ip, offset, size, &imap);
1235                        if (error)
1236                                goto out_unlock;
1237
1238                        xfs_iunlock(ip, lockmode);
1239                }
1240
1241                trace_xfs_get_blocks_alloc(ip, offset, size, 0, &imap);
1242        } else if (nimaps) {
1243                trace_xfs_get_blocks_found(ip, offset, size, 0, &imap);
1244                xfs_iunlock(ip, lockmode);
1245        } else {
1246                trace_xfs_get_blocks_notfound(ip, offset, size);
1247                goto out_unlock;
1248        }
1249
1250        if (imap.br_startblock != HOLESTARTBLOCK &&
1251            imap.br_startblock != DELAYSTARTBLOCK) {
1252                /*
1253                 * For unwritten extents do not report a disk address on
1254                 * the read case (treat as if we're reading into a hole).
1255                 */
1256                if (create || !ISUNWRITTEN(&imap))
1257                        xfs_map_buffer(inode, bh_result, &imap, offset);
1258                if (create && ISUNWRITTEN(&imap)) {
1259                        if (direct)
1260                                bh_result->b_private = inode;
1261                        set_buffer_unwritten(bh_result);
1262                }
1263        }
1264
1265        /*
1266         * If this is a realtime file, data may be on a different device.
1267         * to that pointed to from the buffer_head b_bdev currently.
1268         */
1269        bh_result->b_bdev = xfs_find_bdev_for_inode(inode);
1270
1271        /*
1272         * If we previously allocated a block out beyond eof and we are now
1273         * coming back to use it then we will need to flag it as new even if it
1274         * has a disk address.
1275         *
1276         * With sub-block writes into unwritten extents we also need to mark
1277         * the buffer as new so that the unwritten parts of the buffer gets
1278         * correctly zeroed.
1279         */
1280        if (create &&
1281            ((!buffer_mapped(bh_result) && !buffer_uptodate(bh_result)) ||
1282             (offset >= i_size_read(inode)) ||
1283             (new || ISUNWRITTEN(&imap))))
1284                set_buffer_new(bh_result);
1285
1286        if (imap.br_startblock == DELAYSTARTBLOCK) {
1287                BUG_ON(direct);
1288                if (create) {
1289                        set_buffer_uptodate(bh_result);
1290                        set_buffer_mapped(bh_result);
1291                        set_buffer_delay(bh_result);
1292                }
1293        }
1294
1295        /*
1296         * If this is O_DIRECT or the mpage code calling tell them how large
1297         * the mapping is, so that we can avoid repeated get_blocks calls.
1298         */
1299        if (direct || size > (1 << inode->i_blkbits)) {
1300                xfs_off_t               mapping_size;
1301
1302                mapping_size = imap.br_startoff + imap.br_blockcount - iblock;
1303                mapping_size <<= inode->i_blkbits;
1304
1305                ASSERT(mapping_size > 0);
1306                if (mapping_size > size)
1307                        mapping_size = size;
1308                if (mapping_size > LONG_MAX)
1309                        mapping_size = LONG_MAX;
1310
1311                bh_result->b_size = mapping_size;
1312        }
1313
1314        return 0;
1315
1316out_unlock:
1317        xfs_iunlock(ip, lockmode);
1318        return -error;
1319}
1320
1321int
1322xfs_get_blocks(
1323        struct inode            *inode,
1324        sector_t                iblock,
1325        struct buffer_head      *bh_result,
1326        int                     create)
1327{
1328        return __xfs_get_blocks(inode, iblock, bh_result, create, 0);
1329}
1330
1331STATIC int
1332xfs_get_blocks_direct(
1333        struct inode            *inode,
1334        sector_t                iblock,
1335        struct buffer_head      *bh_result,
1336        int                     create)
1337{
1338        return __xfs_get_blocks(inode, iblock, bh_result, create, 1);
1339}
1340
1341/*
1342 * Complete a direct I/O write request.
1343 *
1344 * If the private argument is non-NULL __xfs_get_blocks signals us that we
1345 * need to issue a transaction to convert the range from unwritten to written
1346 * extents.  In case this is regular synchronous I/O we just call xfs_end_io
1347 * to do this and we are done.  But in case this was a successful AIO
1348 * request this handler is called from interrupt context, from which we
1349 * can't start transactions.  In that case offload the I/O completion to
1350 * the workqueues we also use for buffered I/O completion.
1351 */
1352STATIC void
1353xfs_end_io_direct_write(
1354        struct kiocb            *iocb,
1355        loff_t                  offset,
1356        ssize_t                 size,
1357        void                    *private,
1358        int                     ret,
1359        bool                    is_async)
1360{
1361        struct xfs_ioend        *ioend = iocb->private;
1362
1363        /*
1364         * While the generic direct I/O code updates the inode size, it does
1365         * so only after the end_io handler is called, which means our
1366         * end_io handler thinks the on-disk size is outside the in-core
1367         * size.  To prevent this just update it a little bit earlier here.
1368         */
1369        if (offset + size > i_size_read(ioend->io_inode))
1370                i_size_write(ioend->io_inode, offset + size);
1371
1372        /*
1373         * blockdev_direct_IO can return an error even after the I/O
1374         * completion handler was called.  Thus we need to protect
1375         * against double-freeing.
1376         */
1377        iocb->private = NULL;
1378
1379        ioend->io_offset = offset;
1380        ioend->io_size = size;
1381        ioend->io_iocb = iocb;
1382        ioend->io_result = ret;
1383        if (private && size > 0)
1384                ioend->io_type = XFS_IO_UNWRITTEN;
1385
1386        if (is_async) {
1387                ioend->io_isasync = 1;
1388                xfs_finish_ioend(ioend);
1389        } else {
1390                xfs_finish_ioend_sync(ioend);
1391        }
1392}
1393
1394STATIC ssize_t
1395xfs_vm_direct_IO(
1396        int                     rw,
1397        struct kiocb            *iocb,
1398        const struct iovec      *iov,
1399        loff_t                  offset,
1400        unsigned long           nr_segs)
1401{
1402        struct inode            *inode = iocb->ki_filp->f_mapping->host;
1403        struct block_device     *bdev = xfs_find_bdev_for_inode(inode);
1404        struct xfs_ioend        *ioend = NULL;
1405        ssize_t                 ret;
1406
1407        if (rw & WRITE) {
1408                size_t size = iov_length(iov, nr_segs);
1409
1410                /*
1411                 * We need to preallocate a transaction for a size update
1412                 * here.  In the case that this write both updates the size
1413                 * and converts at least on unwritten extent we will cancel
1414                 * the still clean transaction after the I/O has finished.
1415                 */
1416                iocb->private = ioend = xfs_alloc_ioend(inode, XFS_IO_DIRECT);
1417                if (offset + size > XFS_I(inode)->i_d.di_size) {
1418                        ret = xfs_setfilesize_trans_alloc(ioend);
1419                        if (ret)
1420                                goto out_destroy_ioend;
1421                        ioend->io_isdirect = 1;
1422                }
1423
1424                ret = __blockdev_direct_IO(rw, iocb, inode, bdev, iov,
1425                                            offset, nr_segs,
1426                                            xfs_get_blocks_direct,
1427                                            xfs_end_io_direct_write, NULL, 0);
1428                if (ret != -EIOCBQUEUED && iocb->private)
1429                        goto out_trans_cancel;
1430        } else {
1431                ret = __blockdev_direct_IO(rw, iocb, inode, bdev, iov,
1432                                            offset, nr_segs,
1433                                            xfs_get_blocks_direct,
1434                                            NULL, NULL, 0);
1435        }
1436
1437        return ret;
1438
1439out_trans_cancel:
1440        if (ioend->io_append_trans) {
1441                current_set_flags_nested(&ioend->io_append_trans->t_pflags,
1442                                         PF_FSTRANS);
1443                rwsem_acquire_read(
1444                        &inode->i_sb->s_writers.lock_map[SB_FREEZE_FS-1],
1445                        0, 1, _THIS_IP_);
1446                xfs_trans_cancel(ioend->io_append_trans, 0);
1447        }
1448out_destroy_ioend:
1449        xfs_destroy_ioend(ioend);
1450        return ret;
1451}
1452
1453/*
1454 * Punch out the delalloc blocks we have already allocated.
1455 *
1456 * Don't bother with xfs_setattr given that nothing can have made it to disk yet
1457 * as the page is still locked at this point.
1458 */
1459STATIC void
1460xfs_vm_kill_delalloc_range(
1461        struct inode            *inode,
1462        loff_t                  start,
1463        loff_t                  end)
1464{
1465        struct xfs_inode        *ip = XFS_I(inode);
1466        xfs_fileoff_t           start_fsb;
1467        xfs_fileoff_t           end_fsb;
1468        int                     error;
1469
1470        start_fsb = XFS_B_TO_FSB(ip->i_mount, start);
1471        end_fsb = XFS_B_TO_FSB(ip->i_mount, end);
1472        if (end_fsb <= start_fsb)
1473                return;
1474
1475        xfs_ilock(ip, XFS_ILOCK_EXCL);
1476        error = xfs_bmap_punch_delalloc_range(ip, start_fsb,
1477                                                end_fsb - start_fsb);
1478        if (error) {
1479                /* something screwed, just bail */
1480                if (!XFS_FORCED_SHUTDOWN(ip->i_mount)) {
1481                        xfs_alert(ip->i_mount,
1482                "xfs_vm_write_failed: unable to clean up ino %lld",
1483                                        ip->i_ino);
1484                }
1485        }
1486        xfs_iunlock(ip, XFS_ILOCK_EXCL);
1487}
1488
1489STATIC void
1490xfs_vm_write_failed(
1491        struct inode            *inode,
1492        struct page             *page,
1493        loff_t                  pos,
1494        unsigned                len)
1495{
1496        loff_t                  block_offset = pos & PAGE_MASK;
1497        loff_t                  block_start;
1498        loff_t                  block_end;
1499        loff_t                  from = pos & (PAGE_CACHE_SIZE - 1);
1500        loff_t                  to = from + len;
1501        struct buffer_head      *bh, *head;
1502
1503        ASSERT(block_offset + from == pos);
1504
1505        head = page_buffers(page);
1506        block_start = 0;
1507        for (bh = head; bh != head || !block_start;
1508             bh = bh->b_this_page, block_start = block_end,
1509                                   block_offset += bh->b_size) {
1510                block_end = block_start + bh->b_size;
1511
1512                /* skip buffers before the write */
1513                if (block_end <= from)
1514                        continue;
1515
1516                /* if the buffer is after the write, we're done */
1517                if (block_start >= to)
1518                        break;
1519
1520                if (!buffer_delay(bh))
1521                        continue;
1522
1523                if (!buffer_new(bh) && block_offset < i_size_read(inode))
1524                        continue;
1525
1526                xfs_vm_kill_delalloc_range(inode, block_offset,
1527                                           block_offset + bh->b_size);
1528        }
1529
1530}
1531
1532/*
1533 * This used to call block_write_begin(), but it unlocks and releases the page
1534 * on error, and we need that page to be able to punch stale delalloc blocks out
1535 * on failure. hence we copy-n-waste it here and call xfs_vm_write_failed() at
1536 * the appropriate point.
1537 */
1538STATIC int
1539xfs_vm_write_begin(
1540        struct file             *file,
1541        struct address_space    *mapping,
1542        loff_t                  pos,
1543        unsigned                len,
1544        unsigned                flags,
1545        struct page             **pagep,
1546        void                    **fsdata)
1547{
1548        pgoff_t                 index = pos >> PAGE_CACHE_SHIFT;
1549        struct page             *page;
1550        int                     status;
1551
1552        ASSERT(len <= PAGE_CACHE_SIZE);
1553
1554        page = grab_cache_page_write_begin(mapping, index,
1555                                           flags | AOP_FLAG_NOFS);
1556        if (!page)
1557                return -ENOMEM;
1558
1559        status = __block_write_begin(page, pos, len, xfs_get_blocks);
1560        if (unlikely(status)) {
1561                struct inode    *inode = mapping->host;
1562
1563                xfs_vm_write_failed(inode, page, pos, len);
1564                unlock_page(page);
1565
1566                if (pos + len > i_size_read(inode))
1567                        truncate_pagecache(inode, pos + len, i_size_read(inode));
1568
1569                page_cache_release(page);
1570                page = NULL;
1571        }
1572
1573        *pagep = page;
1574        return status;
1575}
1576
1577/*
1578 * On failure, we only need to kill delalloc blocks beyond EOF because they
1579 * will never be written. For blocks within EOF, generic_write_end() zeros them
1580 * so they are safe to leave alone and be written with all the other valid data.
1581 */
1582STATIC int
1583xfs_vm_write_end(
1584        struct file             *file,
1585        struct address_space    *mapping,
1586        loff_t                  pos,
1587        unsigned                len,
1588        unsigned                copied,
1589        struct page             *page,
1590        void                    *fsdata)
1591{
1592        int                     ret;
1593
1594        ASSERT(len <= PAGE_CACHE_SIZE);
1595
1596        ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
1597        if (unlikely(ret < len)) {
1598                struct inode    *inode = mapping->host;
1599                size_t          isize = i_size_read(inode);
1600                loff_t          to = pos + len;
1601
1602                if (to > isize) {
1603                        truncate_pagecache(inode, to, isize);
1604                        xfs_vm_kill_delalloc_range(inode, isize, to);
1605                }
1606        }
1607        return ret;
1608}
1609
1610STATIC sector_t
1611xfs_vm_bmap(
1612        struct address_space    *mapping,
1613        sector_t                block)
1614{
1615        struct inode            *inode = (struct inode *)mapping->host;
1616        struct xfs_inode        *ip = XFS_I(inode);
1617
1618        trace_xfs_vm_bmap(XFS_I(inode));
1619        xfs_ilock(ip, XFS_IOLOCK_SHARED);
1620        xfs_flush_pages(ip, (xfs_off_t)0, -1, 0, FI_REMAPF);
1621        xfs_iunlock(ip, XFS_IOLOCK_SHARED);
1622        return generic_block_bmap(mapping, block, xfs_get_blocks);
1623}
1624
1625STATIC int
1626xfs_vm_readpage(
1627        struct file             *unused,
1628        struct page             *page)
1629{
1630        return mpage_readpage(page, xfs_get_blocks);
1631}
1632
1633STATIC int
1634xfs_vm_readpages(
1635        struct file             *unused,
1636        struct address_space    *mapping,
1637        struct list_head        *pages,
1638        unsigned                nr_pages)
1639{
1640        return mpage_readpages(mapping, pages, nr_pages, xfs_get_blocks);
1641}
1642
1643const struct address_space_operations xfs_address_space_operations = {
1644        .readpage               = xfs_vm_readpage,
1645        .readpages              = xfs_vm_readpages,
1646        .writepage              = xfs_vm_writepage,
1647        .writepages             = xfs_vm_writepages,
1648        .releasepage            = xfs_vm_releasepage,
1649        .invalidatepage         = xfs_vm_invalidatepage,
1650        .write_begin            = xfs_vm_write_begin,
1651        .write_end              = xfs_vm_write_end,
1652        .bmap                   = xfs_vm_bmap,
1653        .direct_IO              = xfs_vm_direct_IO,
1654        .migratepage            = buffer_migrate_page,
1655        .is_partially_uptodate  = block_is_partially_uptodate,
1656        .error_remove_page      = generic_error_remove_page,
1657};
1658
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